This invention relates to a posterior chamber lens implant which is made of a soft material.
Posterior chamber lens implants which comprise an optical part or lens and two or more holding arms or loops or flanges are known. For example, these lens implants are disclosed and described in European Patent Specification No. 0106488, U.S. Pat. Nos. 4,476,591 and 4,701,181. The arms function to hold the lens implant in place in the capsular bag or the posterior chamber between the posterior capsule and the iris, after the lens implant has been inserted in the eye.
These lens implants are usually made of polymethylmethacrylate (PMMA) which is a hard material which imparts sufficient rigidity to the arms to prevent them from flopping or buckling during or after implantation.
Hydrophilic and silicone rubber materials are however softer and more flexible and do not possess sufficient rigidity to prevent the arms of a lens implant made from such a material from flopping or buckling during use. Thus, to date, lens implants made from a soft material have been provided not with holding arms, but with two opposed flaps for holding the lens implant in place in the eye. For example, these lens implants are disclosed and described in South African Patent No. 84/6570. These flaps do not however provide the same advantages as arms or loops, because forces applied to the flaps are transmitted to the optical part of the lens causing buckling of the lens.
There is thus a need for a new design of lens implant made from a soft material.